Bayer reaction

Furthermore, reaction of three- and four-isomers of the pyridinecarboxaldehyde, in place of two isomer, with N,N-dimethylaniline in the presence of various chiral aluminum complexes gave the diarylated product (16) in moderate yield (Scheme 6.17). In this type of reaction known as the Bayer reaction [19], initially formed alcohol intermediate is more reactive than the starting aldehyde and thus reacts with another molecule of aromatic compound resulting in the diarylated product with loss of water. 

Firouzabadi reported the Bayer reaction of indole and indole derivatives with various aldehydes and ketones catalyzed by heteropoly acid AIPW12O40 (2-7 mol%) in CH3CN at room temperature to give bis(indolyl)methanes [20]. Comparison... 

Acids are usually the end products of ketone oxidations (41,42,44) but vicinal diketones and hydroperoxyketones are apparent intermediates (45). Acids are readily produced from vicinal diketones, perhaps through anhydrides (via, eg, a Bayer-ViUiger reaction) (46,47). The hydroperoxyketones reportedly decompose to diketones as well as to aldehydes and acids (45). Similar products are expected from radical— radical reactions of the corresponding peroxy radical precursors. 

Earlier reports have indicated that esters can form before significant amounts of acids accumulate (16). The Bayer-ViUiger oxidations of ketones with intermediate hydroperoxides and/or peracids have been suggested as ester forming mechanisms (34,56). However, the reactions of simple aUphatic ketones with peracetic acid are probably too slow to support this mechanism (57,58). Very early proposals for ester formation, although imaginative, appear improbable (59). 

X5lenol is an important starting material for insecticides, xylenol—formaldehyde resins, disinfectants, wood preservatives, and for synthesis of a-tocopherol (vitamin E) (258) and i7/-a-tocopherol acetate (USP 34-50/kg, October 1994). The Bayer insecticide Methiocarb is manufactured by reaction of 3,5-x5lenol with methylsulfenyl chloride to yield 4-methylmercapto-3,5-xylenol, followed by reaction with methyl isocyanate (257). Disinfectants and preservatives are produced by chlorination to 4-chloro- and 2,4-dich1oro-3,5-dimethylpheno1 (251). 

The chemical properties of cycHc ketones also vary with ring size. Lower members (addition reactions, than corresponding acycHc ketones. The Cg—C 2 ketones are unreactive, reflecting the strain and high enol content of medium-sized ring systems. Lactones are prepared from cycHc ketones by the Bayer-ViUiger oxidation reaction with peracids. S-Caprolactone is manufactured from cyclohexane by this process ... 

Aluminum. All primary aluminum as of 1995 is produced by molten salt electrolysis, which requires a feed of high purity alumina to the reduction cell. The Bayer process is a chemical purification of the bauxite ore by selective leaching of aluminum according to equation 35. Other oxide constituents of the ore, namely siUca, iron oxide, and titanium oxide remain in the residue, known as red mud. No solution purification is required and pure aluminum hydroxide is obtained by precipitation after reversing reaction 35 through a change in temperature or hydroxide concentration the precipitate is calcined to yield pure alumina. 

PBTC is a water treatment chemical sold by Bayer under the trade name Bayhibit AM. The addition reactions can also be operated as a continuous process... 

Cryolite. Cryofite [15096-52-3] Na AlF, is the primary constituent of the HaH-Hfiroult cell electrolyte. High purity, natural cryofite is found in Greenland, but its rarity and cost have caused the aluminum industry to substitute synthetic cryofite. The latter is produced by the reaction of hydrofluoric acid [7664-39-3] HE, with sodium aluminate [1302-42-7] NaA102, from the Bayer process... 

Thus operating cells need aluminum fluoride [7784-18-17, AIF., rather than cryoHte. Much aluminum fluoride is produced in a fluidized bed by the reaction of hydrofluoric acid gas and activated alumina made by partially calcining the alumina hydrate from the Bayer process... 

Aluminum fluoride is also made by the reaction of fluosiUcic acid [16961 -83-4] H2SiFg, a by-product from phosphoric acid production (see Phosphoric ACID AND THE PHOSPHATES), and aluminum hydroxide from the Bayer process. 

Causticization, the reaction of hydrated lime [1305-62-0], Ca(OH)2, with sodium carbonate to regenerate sodium hydroxide and precipitate calcium carbonate, is an important part of the Bayer process chemistry. 

Small amounts of sodium aluminate are prepared in the lab by fusion of equimolar quantities of sodium carbonate [497-19-8] and aluminum acetate [139-12-8], A1(C2H202)3, at 800°C (4). Other methods involve reaction of sodium hycboxide with amorphous alumina or aluminum [7429-90-5] metal. Commercial quantities of sodium aluminate are made from hydrated alumina, in the form of aluminum hydroxy oxide [24623-77-6], AIO(OH), or aluminum hycboxide [21645-51 -2], Al(OH)3, a product of the Bayer process (5,6) which is used to refine bauxite [1318-16-7], the principal aluminum ore. 

Butyl and Halobutyl Rubber. Butyl mbber is made by the polymerization of isobutylene a small amount of isoprene is added to provide sites for curing. It is designated HR because of these monomers. Halogenation of butyl mbber with bromine or chlorine increases the reaction rate for vulcanization and laminates or blends of halobutyl are feasible for production of mbber goods. It is estimated that of the - 100 million kg of butyl (UR) and halobutyl (HIIR) mbber in North America, over 90% is used in tire apphcations. The halogenated polymer is used in the innerliner of tubeless tires. Butyl mbber is used to make innertubes and curing bladders. The two major suppHers of butyl and halobutyl polymers in North America are Exxon and Bayer (see ELASTOLffiRS,SYNTHETIC-BUTYLrubber). 

Acetylsalicylic acid [50-78-2] (i9-acetyoxyben2oic acid) was first synthesized in 1853 by reaction of acetyl chloride with sodium saUcylate. As a dmg, acetylsahcyhc acid was introduced in Germany in 1899 and into the United States in 1900. The first U.S. patent (35) for the manufacture of acetylsaUcyhc acid expired in 1917. Aspirin is a registered trademark of Bayer in many nations, but in the United States and the United Kingdom, aspirin is accepted as the generic name for acetylsahcyhc acid (36). 

The late 1950s saw the emergence of cast elastomers, which led to the development of reaction injection mol ding (RIM) at Bayer AG in Leverkusen, Germany, in 1964 (see Plastics processing). Also, thermoplastic polyurethane elastomers (TPUs) and Spandex fibers (see Fibers, elastomeric) were introduced during this time. In addition, urethane-based synthetic leather (see Leather-LIKEmaterials) was introduced by Du Pont under the trade name Corfam in 1963. 

In the manufacture of highly resident flexible foams and thermoset RIM elastomers, graft or polymer polyols are used. Graft polyols are dispersions of free-radical-polymerized mixtures of acrylonitrile and styrene partially grafted to a polyol. Polymer polyols are available from BASF, Dow, and Union Carbide. In situ polyaddition reaction of isocyanates with amines in a polyol substrate produces PHD (polyhamstoff dispersion) polyols, which are marketed by Bayer (21). In addition, blending of polyether polyols with diethanolamine, followed by reaction with TDI, also affords a urethane/urea dispersion. The polymer or PHD-type polyols increase the load bearing properties and stiffness of flexible foams. Interreactive dispersion polyols are also used in RIM appHcations where elastomers of high modulus, low thermal coefficient of expansion, and improved paintabiUty are needed. 

Polyester carbonate resins are made by the interfacial process described for standard PC resins. The phthalate units are introduced by reaction of the appropriate phthaloyl dichlorides concurrent with the phosgenation. At present, Bayer, GE, and Miles produce polyester carbonate resins (47) sales volume is low, probably ca 100 t/yr. Polyester carbonates are used primarily in appHcations requiring 5—25°C higher heat-deflection temperature and better hydrolytic performance than are provided by standard PC resins. Properties are given in Table 9. 

In the modified Raschlg process , used by Bayer A.G. and by Mobay Chem. Co. for large scale production of hydrazine, the intermediacy of an oxaziridine could be clearly evidenced (81MI50800). In this process ammonia and hypochlorite are reacted in the presence of acetone to form ketazine (302). Nitrogen-nitrogen bond formation is faster by a factor of about 1000 in the presence of acetone than in its absence. Thus acetone does not merely trap hydrazine after formation, but participates in the N —N bond forming reaction. Very fast formation of oxaziridine (301), which is isolable, is followed by its likewise fast reaction with ammonia. 

The Batch Reaction Subcommittee was chaired by Walter L. Lrank of EQE International. Current members of the subcommittee, listed alphabetically are David J. Christensen, Union Carbide Corporation Warren Greenfield, International Specialty Products Philip P. Malkewicz, Nalco Chemical Company Peter L. McGrath, Olin Corporation Louisa A. Nara, Bayer Corporation Leslie A. Seller, CCPS Staff Consultant Robert Schisla, Eastman Chemical Company Anthony Torres, Eastman Kodak Company Dr. Jan C. Windhorst, Nova Chemicals and Paul Wood, Eli Lilly Company. Eormer subcommittee members who contributed much in getting this project started were Eelix Ereiheiter, CCPS Staff Consultant (deceased) A1 Noren, Monsanto Company-Searle (deceased) John Noronha, Eastman Kodak Company (retired) and Robert Stankovich, Eli Lilly Company. 

The earliest preparation of cellulose acetate is credited to Schiitzenberger in 1865. The method used was to heat the cotton with acetic anhydride in sealed tubes at 130-140°C. The severe reaction conditions led to a white amorphous polymer but the product would have been severely degraded and the process difficult to control. Subsequent studies made by Liebermann, Francimont, Miles, the Bayer Company and by other workers led to techniques for controlled acetylation under less severe conditions. 

In a further vtu iation developed by Bayer, hydrazine (NH2NH2) is dissolved in the polyol and then allowed to react during the foaming stage with some of the 80/20 TDI present. This is of the form of reaction (2) shown in Section 27.2 and this leads to a polyurea of general form ... 

In the absence of solvents and with suitable catalysts the evolution of carbon dioxide simultaneously with the polycarbodi-imide formation gives rise to a foamed product. These foams are cross-linked because of reactions between carbodi-imide groups and free isocyanate groups. Raw materials for such foams are now available from Bayer (Baymid). 

Giirtler and Jautelat of Bayer AG have protected methods that use chloroalumi-nate(III) ionic liquids as solvents for both cyclization and polymerization reactions of acyclic dienes [52]. They employed the neutral ionic liquid [EMIM][G1-A1G13]... 

The reaction conditions are approximately 100-120°C and 15-25 atmospheres. The oxidation step is noncatalytic and occurs at approximately 200°C and 60 atmospheres. An acetic acid yield of 58% could he obtained. By-products are formic acid (6%), higher boiling compounds (3%), and carbon oxides (28%). Figure 9-1 shows the Bayer AG two-step process for producing acetic acid from n-butenes. ... 

Phenol-formaldehyde resins are the oldest thermosetting polymers. They are produced by a condensation reaction between phenol and formaldehyde. Although many attempts were made to use the product and control the conditions for the acid-catalyzed reaction described by Bayer in 1872, there was no commercial production of the resin until the exhaustive work by Baekeland was published in 1909. In this paper, he describes the product as far superior to amber for pipe stem and similar articles, less flexible but more durable than celluloid, odorless, and fire-resistant. ° The reaction between phenol and formaldehyde is either base or acid catalyzed, and the polymers are termed resols (for the base catalyzed) and novalacs (for the acid catalyzed). 

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